Wednesday, May 13, 2015

FrankenChicken

How Bird Beaks Got Their Start As Dinosaur Snouts

Scientists say they have reversed a bit of bird evolution in the lab and re-created a dinosaurlike snout in developing chickens.

"In this work, we can clearly see a comeback of the characteristics which we see in some of the first birds," says Arhat Abzhanov, an evolutionary biologist at Harvard University.

The ancestors of birds are a group of dinosaurs that includes the
famous velociraptor, Abzhanov says. This group of meat-eaters had long
snouts, small brains and eyes, and lots of teeth. Somehow they
transformed into birds, which have none of those things.

Bhart-Anjan Bhullar,
another member of the research team at Yale University, says the goal
is to understand exactly how birds became birds. "What's the deep
history of birdiness?" wonders Bhullar. "How did the different parts of
their body plan form?"

In particular, he and his colleagues are
interested in birds' distinctive beak, which Bhullar calls "this insane
sort of snout that they have."

To hunt for clues about the
origin of the beak, the researchers have been studying various kinds of
animal embryos, from birds like emus and chickens to nonbird reptiles
like alligators, which are birds' closest living relatives.

Their
work led them to two specific genes. These genes are active in the
middle of the face-forming region of bird embryos, but not in the middle
of that region in the embryos of other animals.

The team did an experiment to see what would happen if they blocked the
effect of that localized gene activity in chicken embryos.

Bhullar says he remembers the night he put the altered, developing
chicks under a microscope, and saw that they had unusual, broad snouts.

"That was a pretty remarkable moment," he recalls. "That's a moment that will stay with me, I think."